chore: OOM hardening - lower heap to 4GB, disable sourcemaps (v1.15.8)

Dockerfile

@@ -31,6 +31,9 @@ ENV DATABASE_URI=$DATABASE_URI
 ENV PAYLOAD_SECRET=$PAYLOAD_SECRET
 ENV SKIP_RUNTIME_ENV_VALIDATION=true
 ENV NEXT_BUILD_WORKERS=1
+ENV NEXT_DISABLE_SOURCEMAPS=true
+ENV SENTRY_SKIP_LOCAL_SOURCES=true
+ENV NEXT_PRIVATE_LOCAL_WEBPACK=true
 ENV CI=true
 
 # Copy manifest files specifically for better layer caching
@@ -60,8 +63,8 @@ RUN echo "Building with ID: ${BUILD_ID}"
 COPY . .
 
 # Build application (monorepo filter)
-ENV NODE_OPTIONS="--max_old_space_size=8192"
-RUN pnpm --filter @mintel/web build
+ENV NODE_OPTIONS="--max_old_space_size=4096"
+RUN NEXT_BUILD_WORKERS=1 pnpm --filter @mintel/web build
 
 # Stage 2: Runner
 FROM git.infra.mintel.me/mmintel/runtime:latest AS runner